As public transit ridership continues to wane in San Diego County and beyond, officials have started rolling out the first significant changes to the region’s bus routes in a decade.

On Monday, the San Diego Metropolitan Transit System announced changes to dozens of lines, intended to increase frequency along high-demand corridors.

“We know that frequency and speed of service are the keys for our current riders and attracting new riders,” Paul Jablonski, MTS chief executive officer said in a statement. “We are investing into our system to make it as convenient and efficient as possible.”

Like many transit agencies around the country, MTS saw increases in ridership start slipping in the last two years. Passengers of public transit took about 96,700,000 trips in 2015, up from fewer than 76,860,000 in 2005. But by 2017, that number had dropped back down to about 88,200,000.

While the dip in ridership has cut into revenue from ticket sales, MTS has secured an additional $2 million for the bus system in its next fiscal budget, including from the state’s new gas tax and other sources.

“We need to invest more in our public transit system to reverse the current trend,” said Roberto Torres, spokesman for San Diego City Councilwoman Georgette Gómez, who chairs the MTS board of directors. “Cities like Houston and Seattle invested in their transit system and have seen large increases in their ridership.”

Roughly half of the changes under the MTS Transit Optimization Plan are now in effect, with the bulk of adjustments expected to be rolled out by the end of the summer. In all, about 60 of the agency’s 95 bus routes will be altered in some way.

By fall, more than 30 routes will arrive every 15 minutes or less, and the most popular ones will arrive every 12 minutes or less during rush-hour commutes, said MTS spokesman Rob Schupp.

“We’re putting money into our system where it matters most, where we can attract the most riders,” he said. “In all our research, passengers wanted more frequent service and faster trips. They’d walk twice as far to get to a bus that came more often and gave them a quicker trip.”

The optimization plan was approved by the MTS board in September after roughly 6,000 surveys, more than 50 outreach events and a public hearing on the issue. To see the changes online, go to sdmts.com/top.

The overhaul of the bus system will likely be inconvenient for some riders but is aimed at improving the popularity of transit in the region, said Colin Parent, executive director of the transportation think tank Circulate San Diego.

"MTS's service changes create some winners and losers, but they're overall a good move for system,” he said. “Studies across the country have shown that improvements to service frequency can be a big motivator to get new users for transit."

Route 11 — which includes Skyline Hills, Valencia Park, Southcrest, Logan Heights, Downtown, Hillcrest, University Heights, Normal Heights and San Diego State University — was split into two routes, now 11 and 12, in an attempt to improve reliability.